Simulating Climate with the Most Powerful Supercomputer in the World

UH Manoa researchers are using the latest technology to predict future climates

The International Pacific Research Center (IPRC), the climate center at the University of Hawaiʻi, is collaborating with Japanese scientists on analyses of climate data from Japan‘s Earth Simulator, the most powerful supercomputer in the world. IPRC scientists and lead scientists of the Earth Simulator Center (ESC) and Frontier Research Center for Global Change (FRCGC) of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) met last week at the University of Hawaiʻi to discuss initial results and further collaboration.

The Earth Simulator, with its over 35 trillion calculations per second, is revolutionizing climate research. Global climate models have been limited greatly by lack of computing power and have had to use resolutions somewhere between 200-300 kilometers for the atmosphere, allowing only blurred pictures of Earth‘s climate. These low-resolution models cannot take full advantage of the high-resolution satellite observations, which have been available now for some time. The Earth Simulator is now pushing climate models to match the resolution of observations from space and is breaking new ground for modelers to exploit available data. Testing these new well-resolved numerical models against satellite observations is critical for gaining confidence in their projection of regional features of ongoing global warming.

"Models being run on the Earth Simulator are beginning to also change our views of the ocean, the memory of climate," says Shang-Ping Xie, a lead scientist with the IPRC and meteorology professor at the University of Hawaiʻi. "Currents at 500 meters and more below the surface are largely unknown."

At the IPRC — JAMSTEC meeting, the initial results of a high-resolution ocean model simulation on the Earth Simulator revealed surprising swift currents that alternate in narrow bands between eastward and westward flows at great depths. These currents persist for years and extend over much of the Pacific Ocean. This finding will stimulate oceanographers and guide them in charting these deep ocean jets.

Slow variations in the upper 500 meters of the ocean are associated with movement of huge amounts of heat from one region to another, affecting, for example, the paths and intensities of storms. An astonishing result from the Earth Simulator is that these slow ocean variations are highly organized in space and concentrated along narrow fronts across which ocean surface.

"This is rather unexpected, since the wind changes driving the ocean are much broader, 1,000 kilometers or more," according to Masami Nonaka of the FRCGC.

This new knowledge will help climate and fisheries scientists in designing observation systems to monitor changes in these fronts and in their location.

With its highly skilled team in atmospheric and ocean modeling and in analyzing satellite data, the IPRC is well positioned to take advantage of this new frontier created by the Earth Simulator. By weaving information from the Earth Simulator together with satellite observations from space and observations coming from a new ocean measurement project, the Argo project involving several thousand floats, scientists will be able to fast forward to see what the climate in places like Hawaiʻi may be like in the next several decades.

ABOUT THE EARTH SIMULATOR

In March 2002, Japan powered up the Earth Simulator, which quickly reached a capacity to do over 35 trillion calculations a second, and thereby became the fastest supercomputer in the world (http://www.time.com/time/2002/inventions/rob_earth.html), indeed as powerful as the next 12 fastest supercomputers together. Two years later, the Earth Simulator is still by far the fastest supercomputer (http://www.top500.org/).

Science has been directed towards breaking down physical phenomena into pieces in order to understand their nature, processes, and principles. But each variable is complexly interconnected with others and reductionism often rules out those interactions. The idea behind Japan‘s building of this $350-million supercomputer is that with such a powerful computer, it is possible to input the interrelated variables comprising the whole-earth system and simulate the true nature of the planet.

Tetsuya Sato, Director General of the ESC, says on the ESC Web site (http://www.es.jamstec.go.jp/), "With the Earth Simulator, we are now able to search in territories where no intellectual creation of humankind was ever possible, being able to understand the Earth with all factors entangled together simultaneously, from the micro process of how clouds or snow has been formed, to the macro process of atmospheric circulation, just the way Earth is."

ABOUT THE INTERNATIONAL PACIFIC RESEARCH CENTER

The International Pacific Research Center is an international climate research center that was established under the "Japan-United States Common Agenda for Cooperation in Global Perspective" to promote understanding of the nature and predictability of climate in the Asia Pacific region. The center was founded in October 1997 within the School of Ocean and Earth Science and Technology at the University of Hawaiʻi at Mānoa. It is funded by governmental agencies in Japan and the United States and by the University of Hawaiʻi. Further information about the IPRC is available at http://iprc.soest.hawaii.edu/.